Lubricating oil composition

Abstract

A lubricant composition contains a lubricant base oil, (A) a detergent containing magnesium, (B) a compound containing boron, and (C) a zinc dialkyl dithiophosphate. The amount of component (A) is in the range of 200 to 1200 mass ppm [Mg] based on the mass of the lubricant composition, and the amount of component (C) is in the range of 300 to 1000 mass ppm [P] based on the mass of the lubricant composition. Component (C) includes a zinc dialkyl dithiophosphate having a primary alkyl group or a secondary alkyl group; the lubricant composition includes zinc dialkyl dithiophosphate having a secondary alkyl group; the mass ratio of the zinc dialkyl dithiophosphate having a primary alkyl group and the zinc dialkyl dithiophosphate having a secondary alkyl group is from 70:30 to 0:100; and the concentration of [B] is from 100 to 300 mass ppm based on the mass of the lubricant composition.

1 . A lubricating oil composition comprising a lubricant base oil, (A) a detergent containing magnesium, (B) a boron-containing compound, and (C) a zinc dialkyldithiophosphate, wherein an amount of component (A) is from 200 to 1200 ppm by weight in terms of a magnesium concentration [Mg] which is ppm by weight of magnesium based on the lubricating oil composition;
 an amount of component (C) is from 300 to 1000 ppm by weight in terms of a phosphorus concentration [P] which is ppm by weight of phosphorus based on the lubricating oil composition;   component (C) is one or more selected from zinc dialkyldithiophosphates having a primary alkyl group and/or a secondary alkyl group, wherein the lubricating oil composition comprises at least one zinc dialkyldithiophosphate having a secondary alkyl group, and a weight ratio of a zinc dialkyldithiophosphate having a primary alkyl group to a zinc dialkyldithiophosphate having a secondary alkyl group is from 0/100 to 70/30; and   a boron concentration [B] is from 100 to 300 ppm by weight based on the lubricating oil composition.   
     
     
         2 . The lubricating oil composition according to  claim 1 , wherein the lubricating oil composition comprises at least one ashless dispersant containing boron as the boron-containing compound (B). 
     
     
         3 . The lubricating oil composition according to  claim 1 , wherein the lubricating oil composition further comprises a detergent (A′) containing calcium, and satisfies the following equation (1):
   {[Mg]/([Mg]+[Ca])}×100≥5  (1)
 
 where [Ca] represents a concentration of calcium in terms of ppm by weight based on the lubricating oil composition. 
 
     
     
         4 . The lubricating oil composition according to  claim 1 , further comprising a friction modifier containing molybdenum, and satisfies the following equation (2):
   [Mg]/[Mo]<2.5  (2)
   where [Mo] represents a concentration in terms of ppm by weight of molybdenum based on the lubricating oil composition.   
     
     
         5 . The lubricating oil composition according to  claim 1 , wherein the lubricating oil composition has a CCS viscosity of not more than 6.2 Pa·s at −35° C. 
     
     
         6 . The lubricating oil composition according to  claim 1 , wherein the lubricating oil composition has a high-temperature high-shear viscosity (HTHS viscosity) of 1.5 to 2.9 mPa·s at 150° C. 
     
     
         7 . The lubricating oil composition according to  claim 1 , wherein the lubricating oil composition has a kinematic viscosity of less than 9.3 mm 2 /s at 100° C. 
     
     
         8 . The lubricating oil composition according to  claim 1 , wherein the lubricating oil composition is for use in an internal combustion engine. 
     
     
         9 . The lubricating oil composition according to  claim 2 , wherein the lubricating oil composition further comprises a detergent (A′) containing calcium, and satisfies equation (1):
   {[Mg]/([Mg]+[Ca])}×100≥5  (1)
 
 where [Ca] represents a concentration of calcium in terms of ppm by weight based on the lubricating oil composition. 
 
     
     
         10 . The lubricating oil composition according to  claim 2 , further comprising a friction modifier containing molybdenum, and satisfies equation (2):
   [Mg]/[Mo]<2.5  (2)
   where [Mo] represents a concentration in terms of ppm by weight of molybdenum based on the lubricating oil composition.   
     
     
         11 . The lubricating oil composition according to  claim 2 , wherein the lubricating oil composition has a CCS viscosity of not more than 6.2 Pa·s at −35° C. 
     
     
         12 . The lubricating oil composition according to  claim 2 , wherein the lubricating oil composition has a high-temperature high-shear viscosity (HTHS viscosity) of 1.5 to 2.9 mPa·s at 150° C. 
     
     
         13 . The lubricating oil composition according to  claim 2 , wherein the lubricating oil composition has a kinematic viscosity of less than 9.3 mm 2 /s at 100° C. 
     
     
         14 . The lubricating oil composition according to  claim 2 , wherein the lubricating oil composition is for use in an internal combustion engine. 
     
     
         15 . The lubricating oil composition according to  claim 3 , further comprising a friction modifier containing molybdenum, and satisfies equation (2):
   [Mg]/[Mo]<2.5  (2)
   where [Mo] represents a concentration in terms of ppm by weight of molybdenum based on the lubricating oil composition.   
     
     
         16 . The lubricating oil composition according to  claim 3 , wherein the lubricating oil composition has a CCS viscosity of not more than 6.2 Pa·s at −35° C. 
     
     
         17 . The lubricating oil composition according to  claim 3 , wherein the lubricating oil composition has a high-temperature high-shear viscosity (HTHS viscosity) of 1.5 to 2.9 mPa·s at 150° C. 
     
     
         18 . The lubricating oil composition according to  claim 3 , wherein the lubricating oil composition has a kinematic viscosity of less than 9.3 mm 2 /s at 100° C. 
     
     
         19 . The lubricating oil composition according to  claim 3 , wherein the lubricating oil composition is for use in an internal combustion engine. 
     
     
         20 . The lubricating oil composition according to  claim 4 , wherein the lubricating oil composition has a CCS viscosity of not more than 6.2 Pa·s at −35° C.